Reproducing apparatus



Jan. 29, 1952 w. R. JACOBSON 8 REPRODUCING APPARATUS Filed May 4, 1950 2SHEETS SI'IEET l Inve ntor:

Woodrow R. Jacobson,

b 14. 4M4 y Attoi rzeyn' 2 I w. R. JACOBSON ,7

' REFRODUCING APPARATUS Filed May 4, 1950 2 SHEETS-SHEET 2 b I I WAVELENGTH 40 4s 3 l I AMPLIFIER RECTIFIER POWER SUPPLY Inve ntor: WooigwR. Jacob s on, by M 4:-

His Attorney.

Patented Jan. 29, 1952 REPRODUCING APPARATUS Woodrow R. Jacobson,Schenectady, N. Y., asslgnor to General Electric Company, a corporationof New York Application May 4, 1950, Serial No. 159,958

3 Claims.

My invention relates to picture reproducing apparatus and, moreparticularly, to apparatus for automatically producing color separationne atives, which are black and white negatives in which the blackportion represents a particular shade of color in a picture beingreproduced and the white portion represents all other colors.

In the field of printing and, more specifically, in the field ofprinting a design on wallpaper or perhaps a design on print cloth, it iscustomary to print the design on the paper or the cloth by passing thematerial to be printed over lithographic cylinders, each cylinderprinting on the material one shade of color of the final picture.Because color separation negatives which are used in the photo-etchingof lithographic cylinders are presently made entirely by hand artwork,the time, and, hence, the expense of making such negatives is extremelyhigh.

At present, the artist making a color separation negative places atransparent sheet of material over an original artists sketch and withbrush and ink draws a pattern which is a copy of a particular colorpattern. This process is repeated a number of times equal to the numberof diiferent colors in the sketch, and these reproductions are thenused. to make black and white photographic negatives.

It is, therefore, an object of my invention to provide new and improvedapparatus which automatically produces color separation negatives of anoriginal artist's sketch.

A major problem arising in automatic reproduction of color separationnegatives is the inability of the apparatus to scan the sketch and tohave the sensing element respond to only one preselected color. Allother colors should cause no signal whatever in the detecting elementsince there must be no half-tones in a final color separation negative.

According to the illustrated embodiment of my invention, I provide anautomatic color scanner which obviates the use of highly skilledpersonnel in the production of color separation negatives. In myapparatus, a beam of light is made to scan the picture to be reproducedand another beam of light is made to scan in corresponding manner alight sensitive photographic film. Due to an electronic circuit, thebeam of lightexciting the photographic film is only pres ent when'apredetermined color in the picture is being scanned. Consequently, thepattern which is recorded on the photographic film is an exact replicain black and white of a particular color pattern in the original pictureorsketch being reproduced. The original sketch to be reproduced isscanned a number of times equivalent to the number of different colorsin the sketch, and an equal number of negatives are produced. For eachindividual negative, an operator makes a few adjustments to theapparatus, such that the scanning unit responds to a predetermined coloronly, and without further attention during the actual scanning time thephotographic film is automatically exposed.

For additional objects and advantages, and for a better understanding ofmy invention, attention is now directed to the following description andaccompanying drawing, and also the appended claims, in which thefeatures of my invention believed to be novel are particularly pointedout, in which Fig. 1 is a pictorial view of apparatus built according tomy invention; Fig. 2 is a schematic view of the scanning unit of theapparatus in Fig. 1; Fig. 3 is a graph of a number of spectrophotometriccurves which may be applied to a picture being photographed by theapparatus of Fig. 1; and Fig. 4 is a schematic electric diagram of alight modulator circuit applicable to the apparatus of Fig. 1.

Referring to Fig. l, a recording cylindrical drum I has mounted on itsouter surface a photographic film 2, such that the light sensitiveemulsion on the film is exposed, and a scanning cylindrical drum 3 hasmounted on its outer surface a picture 4 which is to be reproduced.Drums I and 3 are mounted on shafts 5 and 5 respectively, and theseshafts are supported in bearing supports 1, B, 9 and In, such thatcylinders I and 3 are rotatable about shafts 5 and 6. An electric motorH has mounted on its shaft gears l2, l3 and M. A gear l5, mounted onshaft 5, intermeshes with gear [2, and a gear I61, mounted on shaft 6,intermeshes with gear M. A scanning unit I! is mounted on a jackscrew itwhich is free to rotate in supports I9 and 20, and on a guide 2| whichis supported by supports 22 and 23. A gear 24, which intermeshes withgear I3, is mounted on the extension of screw it, and rotation of thisgear results in the movement of unit I! in a direction parallel to thelongitudinal axes of cylinders l and 3. Rotation of the rotor of motorll, therefore, results in the rotation of cylinder 1, cylinder 3, andthe linear movement of scanning unit ll.

As is well-known in the art, rotation of the shafts. By making the gearratio between gears I2 and 5 and between gears l4 and I6 equal,corresponding points on the opposite faces of unit I! adjacent tocylinders and 3 scans corresponding points on the cylinders and, hence,on the picture and film mounted on the cylinders.

As the scanning unit moves across the surfaces 1 of the two drums,picture 4 is scanned by a pickup section and, at the same time, areproducing section emits a beam of light onto a corresponding point ofthe film 2. When a particular predetermined color on picture 4 is beingscanned, a light is emitted. from the reproducing section of unit I!which intercepts film 2. When, however, the pick-up section of unit I!scans a different color on picture 4, no light is focused from thereproducing section on film 2.

Referring to Fig. 2, in which the pick-up and reproducing sections areillustrated, a source of light 25 emits rays of light, some of which arefocused by lenses 26 and 21 to a small spot on the surface of picture i.A cross-over in the focused rays from lens 26 occurs at point 28. Thoselight rays emitted by source 25 and reflected from picture 4 are focusedby means of lenses 29 and 39 to the light sensitive cathode of aphototube 3|. A serrated disk 32,- mounted on a shaft 33 such that it isfree to rotate about its longitudinal axis, is positioned such that itsserrated circumference intercepts those light rays focused by lens 25 ata point close to cross-over point 28, and shaft 33 is rotated'by meansof an electric motor 34. A lens 35 focuses light rays emitted by source25 and reflected from disk 32 to the photosensitive cathode of phototube3|. Polaroid lenses 35 and 3?, which lie in the path of this reflectedlight, have coinciding longitudinal axes and polaroid 31 is rotatableabout this axis by means of knob 38. As well known in the art, polaroidlenses mounted in this manner may be used as a light attenuator. Amodulator lamp 39 emits light rays which are reflected from mirror 40and focused by lens 4| to a point on the light sensitive emulsion ofphotographic film 2, which corresponds to the point on picture 4reflecting the beam of light from source 25. lindrical hole 42 isthreaded such that it matches the thread of jackscrew l8 and cylindricalhole 43 surrounds guide 2| and guides the scanning unit along itslateral path. V

In Fig. 3, curve A is the percent reflectance versus wave length oflight striking a dark blue surface, curve B is a similar curve forlight'striking a light blue surface, curve C is a similar curve forlight striking a red surface, and curve D is a similar curve for lightstriking a white surface. It can be seen from these curves that forlight of any particular wave length the percent reflectance for thevarious colors diflers and, therefore, the intensity of light reflectedby these colors will differ.

Referring again to Fig. 2, disk 32 is rotated by motor 34 such thatduring one interval of time, light passes through theserrations of thedisk toward lens 2?, while during a following interval of time the lightfrom source 25 is reflected from a tooth on disk 32 and focused by lens35 on the cathode of tube 3|. The serrations on disk 32 may be such thatthe intensity of the light passed by the disk is a sine Wave ofintensity of light 7 versus t1me in which the time of one cycle of thewave is the time required for successive serrations to pass any pointalong the path of the circumference of disk 32, and, conversely, the

cosine wave having a wavelength equal. to the wavelength of the passedwave. Because the sum of a sine wave and a cosine wave having the samefrequency and the same amplitude is a constant, when the beam of lightimpinging on the cathode of tube 3| from picture 4 has the sameintensity as the beam of light impinging on the cathode of tube 3| fromdisk 32, the current or voltage output of tube 3| has no alternating orripple component.

A color wheel 44 has arranged about its perimeter a plurality ofdifferent narrow bandwidth color filters t5, any one of which byrotation of wheel 44 about pivot 46 can be made to interceptthe-reflected light from picture 4. It will be noted in the drawing thatthe color filters may intercept both that beam of light reflected frompicture 4 and that beam reflected from serrated disk 32; however, thisis unnecessary, and only that beam of light reflected from picture 4need be filtered. This fact will be made evident hereinafter. Colorfilters 45 are narrow bandwidth filters or nionochromatizing filters inwhich only an extremely narrow band of wavelengthsis passed such thatthe beam of light striking tube 3| from picture 4 is essentially of onlyone color.

If it is desired to produce a black and white negative indicative of thedark blue color in picture 4, a filter passing a narrow band ofwavelengths in the vicinity of 475 Angstroms may be used to interceptthe reflected beam. From Fig. 3 it can be seen that such a filter willthen pass a narrow band of wavelengths of light which has an intensityof approximately 20% reflectance when a dark blue color is scanned. Withthis filter, a light blue color will reflect light which has areflectance of approximately 50% while a red color will reflect lighthaving a reflectance of about 2%. By the proper adjustment of theangular position of polaroid lens 31, the light beam reflected fromserrated disk 32 to phototube 3| may be attenuated such that it has anamplitude equal to a beam of light reflected from a surface having a 20%reflectance. Consequently, any light from a dark blue surface will beexactly compensated for by the light reflected from serrated disk 32 andno ripple voltage will appear in the output of phototube 35. If,however, during the scanning process the light striking picture 4 fallson another color, such, for example, as light blue, the amplitude of thelight wave arriving at tube 3| from picture l will bemuch greater thanthe amplitude of the light wave reflected from disk 32 and a largeripple voltage will appear in the output of tube 3|. Similarly, if a redcolor is scanned, the amplitude of the light wave reflected from the redcolor to tube 3| will be much less than the amplitude of the light wavereflected from disk 32 and, once more, a large ripple voltage willappear in the output of tube 3|. It should, therefore, be noted thatonly the amplitude or intensity of the light reflected from disk 32 isused as the reference and it is immaterial whether filter 45 is used asan attenuator to partly adjust this intensity.

Referring to Fig. 4, a power supply 4'! supplies anode voltage tophototube 3|, the output of which is amplified by a conventionalamplifier 48 and supplied to a conventional rectifier 49. Thus, if anyalternating voltage appears in the output 0 of tube 3|, it is amplifiedby amplifier 48 and rectified by rectifier 49;" The direct voltageoutput of rectifier 49 is, thereforegdirectly related to the alternatingcomponent of the output current of tube 3| and this output directvoltage of light reflected from the teeth on the disk is a 7:, rectifier49 is applied as a bias between the control electrode and the cathode ofa conventional amplifying tube 50 in the plate circuit of which is amodulator lamp 391. By the proper selection of tube 50 and the operatingpoints, a very small direct voltage output from rectifier 49 may be usedto cut off tube 50 and, hence, cut off the light from modulator lamp 39.Modulator lamp 39, therefore, emits light rays when no alternatingsignal is applied to rectifier 49, but emits no light when a smallalternating voltage is applied to rectifier 49. Light rays are,therefore, emitted from lamp 39 when a dark blue color is scanned, but,when any other color is scanned, no light rays whatsoever are emitted.Consequently, a black and white negative having no half tones isproduced when photographic film 2 is developed, and the black portionrepresents the dark blue colors in the original sketch while the whiteportion represents all other colors. For a black and white colorseparation negative representing a light blue color, a monochromatizingfilter passing a narrow band width in the vicinity of 510 Angstroms maybe similarly employed and for a negative representing the red colors, afilter passing a narrow band width in the vicinity of 600 Angstroms maybe employed. When the apparatus is adjusted for a different color, thefilter corresponding to the new color desired is moved into the path ofthe light reflected from the picture, and knob 38 is adjusted such thatthe light reflected from disk 32 is attenuated to a value where itsubstantially equals the intensity of light reflected from the desiredcolor.

This apparatus for producing color separation negatives has theadvantage over presently used methods in that it is automatic, itproduces pictures at a relatively rapid rate, the negative is anaccurate reproduction of the original, and one operator may operate anumber of machines at one time. A light-tight cover may, of course, beprovided with this apparatus such that the picture may be scanned in alighted room, although in this case the unexposed photographic filmmight still have to be mounted on the reproducing cylinder in darkness.

While my invention has been described by reference to particularembodiments thereof, it will be understood that this is by way ofillustration of the principles involved and that those skilled in theart may make many modifications in the arrangement and mode ofoperation. Therefore, I contemplate by the appended claims to cover anysuch modifications as fall within the true spirit and scope of myinvention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In combination, a cylindrical scanning drum, a cylindrical recordingdrum, said drums having equal diameters and parallel longitudinal axes,a jackscrew driven scanning unit being located between said drums andhaving a lateral movement parallel to the longitudinal axes of saiddrums, an electric motor for rotating said jackscrew and said drums,said drums being rotated at equal velocities, said scanning unitcomprising a source of light rays, means for focusing some of said raysinto a narrow beam which is incident to said scanning drum, an electrondischarge device being provided with an anode and a light sensitivecathode, the output voltage of said device being dependent upon theintensity of light striking said cathode, means for focusing rays ofsaid beam reflected from said scanning drum on said cathode, a colorwheel being rotatable about its longitudinal axis and having amultiplicity of different narrow bandwidth color filters mounted aboutits periphery, said wheel being located such that one of said filtersintercepts the beam of light reflected from said recording drum, arotatable circular disk having a serrated circumference and beinglocated such that the serrations on said circumference intercept thebeam of light from said source, said serrations being shaped such thatthe amplitude of light transmitted through said disk is a sine wave,means for focusing light rays from said source reflected from saidserrations on said cathode, a variable light attenuator located betweensaid serrations and said cathode, a second source of light rays, meansfor focusing said rays into a narrow beam which is incident to saidrecording drum, and electronic means for controlling the intensity oflight rays from said second source according to variations in thevoltage output from said discharge device.

2. Optical apparatus comprising a first source of light rays, aninterrupter disk located in the path of said rays, means for focusing toa point light rays passed by said interrupter disk, an electrondischarge device provided with an anode and a light sensitive cathode,the output voltage of said device being dependent upon the intensity oflight impinging on said cathode, means for focusing light rays reflectedfrom said point on said cathode, a narrow bandwidth light filter locatedbetween said point and said cathode, means for focusing light raysreflected from said interrupter on said cathode, adjustable lightattenuating means located in the path of said interrupter reflectedlight, a second source of light rays, means for focusing to a secondpoint light rays from said second source, and electronic means forcontrolling light rays emitted from said second source by the variationsin the voltage output of said discharge device.

3. Optical apparatus comprising a first source of light rays, a serratedrotatable interrupter disk being located in the path of said rays,serrations on said disk being shaped such that the intensity of lightpassed by said serrations is a sine wave, means for focusing to a pointlight rays passed by said serrations, an electron discharge deviceprovided with an anode and a light sensitive cathode, the output voltageof said device being dependent upon the intensity of light impinging onsaid cathode, means for focusing light rays reflected from said point'onsaid cathode, a narrow bandwidth light filter located between said pointand said cathode, means for focusing light rays reflected from saidinterrupter on said cathode, said interrupter reflected light having anintensity varying according to a cosine wave, adjustable lightattenuating means located in the path of said interrupter reflectedlight, a second source of light rays, means for focusing to a secondpoint light rays from said second source, and electronic meansresponsive to the voltage output of said discharge device for energizingsaid second source only when the voltage output of said discharge deviceis a predetermined substantially constant value.

WOODROW R. JACOBSON.

REFERENCES CITED UNITED STATES PATENTS Name Date Thompson Jan. 28, 194?Number

